In a statement late on Friday, it said the White House and the Department of Justice had “failed to provide the necessary clarity and assurance to the service providers that are integral to maintaining TikTok’s availability”.

It said that unless the government immediately stepped in to assure the video app it would not be punished for violating the looming ban, it would be “forced to go dark on January 19”.

The statement follows a Supreme Court ruling earlier on Friday which upheld a law banning the app in the US unless its China-based parent company, ByteDance, sells the platform by Sunday.

Passed in April last year, the law says ByteDance must sell the US version of the platform to a neutral party to avert an outright ban.

TikTok challenged the law, arguing it violates free speech protections for its 170 million users in the country.

But the Supreme Court’s ruling means the US version of the app will be removed from app stores and web hosting services unless a buyer is found in the coming days.

It had been thought the ban would not impact TikTok users who already have the app downloaded on their phones.

But given updates would become unavailable once the ban comes into force, the app would eventually degrade and become unusable over time.

TikTok’s fresh statement on Friday,however, suggests it may immediately become unavailable to all existing users as well as those seeking to download it.

Influencers and content creators have been posting videos on the app bidding farewell to their followers ahead of the impending ban.

One creator, Nicole Bloomgarden, told the BBC not being on TikTok would amount to a significant salary cut, while another, Erika Thompson, said the educational content on the platform would be the “biggest loss” for the community.

Some users have been announcing where their content will be available to view next, including on the Chinese video app, Red Note, which has been little used by American users up until now.

• Americans and Chinese share jokes on ‘alternative TikTok’

President Joe Biden’s term is due to end on Monday, with Donald Trump due to be sworn in as the next president on that day. The White House earlier said it would therefore fall on the incoming president to enforce the law.

Trump has indicated he is against the ban, after initially supporting the move. “My decision on TikTok will be made in the not too distant future, but I must have time to review the situation,” he said on Friday.

He also revealed he had spoken to China’s President Xi Jinping and discussed TikTok, among other issues.

In December Trump said he had a “warm spot” for the app as it helped him with young voters in the 2024 election.

Trump’s comments marked a U-turn on his stance in his first term as president when he aimed to enact a similar ban through an executive order.

ByteDance has vowed not to sell TikTok and said it planned to shut US operations of the app on Sunday unless there is a reprieve.

Democratic and Republican lawmakers voted to ban the video-sharing app last year, over concerns about its links to the Chinese government. TikTok has repeatedly stated it does not share information with Beijing.

The potential ban comes at a time of heightened concern in the US about Chinese espionage.

Cybersecurity firms have suggested that the app is capable of collecting users’ data beyond what they look at on TikTok.

US Attorney General Merrick Garland said authoritarian regimes should not have “unfettered access” to Americans’ data and that the decision prevented China from “weaponising TikTok to undermine America’s national security”.

China enacted a law in 2017 that compels Chinese nationals living abroad to co-operate with its intelligence apparatus.

But Beijing has denied it pressures companies to collect information on its behalf and criticised the ban. TikTok has repeatedly stressed it has not been asked for its data.

The app argued the law endangers free speech and would hit its users, advertisers, content creators and employees. TikTok has 7,000 US employees.

TikTok had challenged the law, arguing it would violate free speech protections for the app’s more than 170 million users it says it has in the US.

But that argument was rejected by the nation’s highest court, meaning TikTok must now find an approved buyer for the US version of the app or face being removed from app stores and web hosting services.

However, the outgoing Biden administration and incoming President Donald Trump have been trying to work out a reprieve for the platform, which US authorities have warned poses a national security risk.

Both Democrat and Republican lawmakers voted to ban the video-sharing app last year, over concerns about its links to the Chinese government. TikTok has repeatedly stated it does not share information with Beijing.

The law gives TikTok’s owner, ByteDance, until 19 January to sell the US version of the platform to a neutral party to avert an outright ban.

It would mean that from Sunday Apple and Google will no longer offer the app to new users or provide any security updates to current users – which could kill it off eventually.

The company has vowed not to sell TikTok.

It’s all unfolding on a popular Chinese social media app called RedNote, or Xiaohongshu (literally translates as Little Red Book), which doesn’t have the usual internet firewall that separates China from the rest of the world.

It has been drawing self-professed US “TikTok refugees” seeking a new home on the internet – despite the fact that their own government is seeking a TikTok ban because of national security concerns.

Americans now find themselves in direct contact with 300 million Mandarin speakers in China and elsewhere – while in the real world, Beijing is bracing for a tumultuous Trump presidency that could strain its fragile ties with Washington.

At the heart of the US ban is the fear that China is using TikTok to spy on Americans.

The app has faced accusations that user data is ending up in the hands of the Chinese government – because of a Beijing law that requires local companies to “support, assist and cooperate with the state intelligence work”. TikTok denies this has ever happened, or that it would happen.

But the possibility doesn’t seem to worry some US users – 700,000 new users have signed on to RedNote in the last two days, making it the most downloaded free app in the US App store.

“The reason that our government is telling us that they are banning TikTok is because they’re insisting that it’s owned by you guys, the Chinese people, government, whatever,” said one new RedNote user, Definitelynotchippy.

She goes on to explain why she is on RedNote: “A lot of us are smarter than that though so we decided to piss off our government and download an actual Chinese app. We call that trolling, so in short we’re here to spite our government and to learn about China and hang out with you guys.”

TikTok, although owned by Chinese company ByteDance, is headquartered in Singapore and says it is run independently. In fact, China’s version of TikTok is another app called Douyin. RedNote, on the other hand, is a Chinese company based in Shanghai and among the few social media apps available both in China and outside.

So Washington’s fears over TikTok would extend to RedNote as well.

That’s why American users on RedNote are referring to themselves as “Chinese spies” – continuing a TikTok trend where people have been bidding farewell to their “personal Chinese spy” who has allegedly been surveilling them over the years.

RedNote is now full of posts where ex-TikTok users are in search of a replacement. One post says: “I’m looking for my Chinese spy. I miss you. Please help me find him.”

And Chinese users have answered: “I’m here!”

The honest, funny conversations on RedNote may not be what Chinese President Xi Jinping had in mind when he spoke about “strengthening people-to-people cultural exchanges” between China and the US.

But that is certainly what is happening as excited Chinese users welcome curious Americans to the app.

“You don’t even need to travel abroad, you can just talk to foreigners here,” said one Chinese RedNote user in a video that has received more than 6,000 likes.

“But it’s honestly insane, no-one would have expected that we could meet like this one day, openly communicate like this.”

Food, streaming shows and jobs have been the most popular topics: “Is life in America similar to how it looks on [the US TV show] Friends?”

Other Chinese users demanded a “tax” for using the platform – cat photos.

“Cat tax from California,” reads one post in response. “Here’s my offering – the shorthair is a boy named Bob and the calico is a girl named Marley.”

Still others are using the platform to ask Americans for help with their English homework.

One post reads: “Dear TikTok refugees, could you please tell me the answer to question 53? Is the answer T (true) or F (false)?”

Help came quickly: some 500 people have since answered.

The flood of new American users appears to have caught RedNote off guard – reports say the company is hiring English moderators.

And others are trying to cash in on RedNote’s new-found US stardom as well: language-learning app Duolingo put out a graph showing a 216% jump in its user base, compared to this time last year.

RedNote’s rising popularity is not guaranteed to last though.

There is no reason to assume it won’t face blowback for the same reasons as TikTok: concerns that it could be used by China to spy on Americans.

It’s unclear how long Beijing would be open to such unfettered exchanges – control of the internet is key to its repressive regime.

The irony of the situation was flagged by one Chinese user, who posted: “Don’t we have a (fire)wall? How come so many foreigners can enter, when clearly I can’t leave?”

Typically, Chinese internet users have been unable to directly interact with foreigners. Global platforms like Twitter and Instagram and search engines like Google are blocked in China, though people use VPNs to circumvent these restrictions. Sensitive topics – from history to dissent – or anything seen as critical of China’s government and ruling Communist party is swiftly censored.

It’s unclear how much RedNote is censored – it’s largely used by younger and middle-aged women in China, where they share images and videos. It’s not like Weibo, another Chinese app, where discussions and airing of grievances is far more common, leading to posts often being taken down.

But a handful of new RedNote users say they have already received reports that their posts have violated guidelines, including one who asked in a post if the app was “LGBT friendly”.

Another said they had asked “What [sic] Chinese think about gay people?” and received a similar notification, that they had violated “public moral order” guidelines.

And Chinese users keep reminding Americans on the app “not to mention sensitive topics, such as politics, religion and drugs”.

One Chinese user also advised them to stick to the “One China policy”, the diplomatic pillar of the US-China relationship – according to which the US recognises and has formal ties with China rather than Taiwan, the self-governed island Beijing claims as its own.

The US government has not commented on RedNote so far, and neither has Beijing.

But Chinese state media seems upbeat about it, with Global Times even interviewing a US user who said she would “love to interact with Chinese users”.

RedNote’s American fate is anyone’s guess – but for now, at least online, the US-China rivalry is taking a break. Thanks to cat pictures.

The US government is taking action against the app because of what it says are its links to the Chinese state – links which TikTok and its parent company ByteDance have denied.

The Supreme Court justices did not act on a request by TikTok for an emergency injunction against the law, but will instead allow TikTok and ByteDance to make their case on 10 January – nine days before the ban is due to take effect.

Earlier in December, a federal appeals court rejected an attempt to overturn the legislation, saying it was “the culmination of extensive, bipartisan action by the Congress and by successive presidents”.

The Supreme Court is the highest legal authority in the US, and the decision to take on TikTok’s case is significant as it only hears 100 or so cases a year out of the more than 7,000 petitions it receives.

TikTok had previously argued that the attempt to ban it was unconstitutional because it would impact the free speech of its users in the country.

TikTok said Wednesday it was pleased with the Supreme Court’s order.”We believe the Court will find the TikTok ban unconstitutional so the over 170 million Americans on our platform can continue to exercise their free speech rights,” a TikTok spokesperson said in a statement to the BBC.

The appeal sets up a clash between free speech and national security, according to University of Richmond law professor Carl Tobias.

“The appeals court found that national security was stronger than the First Amendment contentions. However, the Justices will scrutinize the potentially conflicting, but significant, values,” Mr Tobias said in an email.

While it is difficult to predict the outcome, Cornell professor Sarah Kreps said it would be surprising to the court to overturn the prior rulings and go against the wills of both congress and the White House.

“The case has already gone through the executive branch, the legislative branch, and the lower court, all of which upheld the argument that TikTok’s ownership by China-based ByteDance poses a national security risk,” Dr Kreps said.

TikTok’s future does not just hang on the legal process, however – Donald Trump’s victory in the US presidential election may also hand it a lifeline.

He met TikTok boss Shou Zi Chew on Monday at his Mar-a-Lago estate in Florida, CBS News reported, citing sources familiar with the meeting.

Trump has publicly said he opposes the ban, despite supporting one in his first term as president.

But he will not take office until 20 January, the day after the deadline for TikTok to be banned or sold.

“I have a warm spot in my heart for TikTok, because I won youth by 34 points,” he claimed at a press conference on Monday – though a majority of 18 to 29-year-olds backed his opponent Kamala Harris.

“There are those that say that TikTok has something to do with that,” he said.

But despite Trump’s support, senior Senate Republican, Mitch McConnell, urged the Supreme Court to reject TikTok’s bid.

In a brief filed to the court, he called the firm’s arguments “meritless and unsound.”TikTok has the backing of some civil liberties organisations however.

A group of them have made a joint filing to the court urging it to block the banning of a platform which they argue “millions use every day to communicate, learn about the world, and express themselves.”